4,589 research outputs found

    Spongiosolysis

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    Cyclostratigraphy And Sedimentation Of The Cenomanian-Turonian Tuscaloosa Marine Shale

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    A cyclostratigraphic and geochemical analysis was conducted on the basal high resistivity zone of the Tuscaloosa Marine Shale to determine if orbital forcing is apparent in mineralogical data suites. Geochemical data suites obtained via x-ray diffraction from five cored wells located near the southern Mississippi/Louisiana border were used in the study. The results were used in concert with previously published insolation and biostratigraphic data and unpublished stable carbon isotope data to determine sedimentation rate, to identify and correlate the cretaceous oceanic anoxic event 2 (OAE 2) recovery period within the studied interval, and to determine the possible mechanisms of orbital forcing. Results from multitaper spectral analysis and average spectral misfit reveal multiple statistically significant stratigraphic frequencies in four of the five studied wells, as well as significant correlation to orbital cyclicity (p\u3c\u3c 0.05). Sedimentation rates range from 8.811 cm/ky to 12.321 cm/ky and average 10.332 cm/ky. Toc and resistivity values were used to correlate the oae 2 recovery interval between the studied wells. Calculated durations range from 212 ky in the most distal well location to 251 ky in more proximal locations. The published insolation and unpublished stable carbon isotope data were used to anchor the time scale based on the terminus of OAE 2 at approximately 94 ma. Based on geochemical proxies, it is proposed that variations in insolation and the hydrologic cycle drove cyclic sedimentation by varying primary productivity and continental weathering

    L'ichnofaune reptilienne hettangienne du Veillon (Vendée, France)

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    The Veillon ichnofauna, early Liassic in age, includes various Reptile taxa: quadruped Pseudosuchian, Coelurosaurians, Theropods, primitive Iguanodon – like Ornithopods and some unspecified forms. This ichnofauna is very comparable to the early Liassic footprint assemblage of the Connecticut

    Three-dimensional dynamic rupture simulation with a high-order discontinuous Galerkin method on unstructured tetrahedral meshes

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    Accurate and efficient numerical methods to simulate dynamic earthquake rupture and wave propagation in complex media and complex fault geometries are needed to address fundamental questions in earthquake dynamics, to integrate seismic and geodetic data into emerging approaches for dynamic source inversion, and to generate realistic physics-based earthquake scenarios for hazard assessment. Modeling of spontaneous earthquake rupture and seismic wave propagation by a high-order discontinuous Galerkin (DG) method combined with an arbitrarily high-order derivatives (ADER) time integration method was introduced in two dimensions by de la Puente et al. (2009). The ADER-DG method enables high accuracy in space and time and discretization by unstructured meshes. Here we extend this method to three-dimensional dynamic rupture problems. The high geometrical flexibility provided by the usage of tetrahedral elements and the lack of spurious mesh reflections in the ADER-DG method allows the refinement of the mesh close to the fault to model the rupture dynamics adequately while concentrating computational resources only where needed. Moreover, ADER-DG does not generate spurious high-frequency perturbations on the fault and hence does not require artificial Kelvin-Voigt damping. We verify our three-dimensional implementation by comparing results of the SCEC TPV3 test problem with two well-established numerical methods, finite differences, and spectral boundary integral. Furthermore, a convergence study is presented to demonstrate the systematic consistency of the method. To illustrate the capabilities of the high-order accurate ADER-DG scheme on unstructured meshes, we simulate an earthquake scenario, inspired by the 1992 Landers earthquake, that includes curved faults, fault branches, and surface topography

    Structuration cassante de la marge vendéenne au Lias inférieur : exemple de l'estuaire du Payré au sud de Talmont-Saint-Hilaire

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    In the Talmondais (Vendée) the Hettangian sedimentation locally begins with fluviatil clastic deposits prior to the deposition of shallow marine carbonates. These clastics, including the footprint-bearing beds of Le Veillon (south of Talmont- Saint-Hilaire) are subject to important and frequent variations in thickness. Drilling and geophysic data indicate a tectonic control of these variations. A fault-block pattern is proposed. At a small scale, it gives an illustration of the extensional tectonic processes related to the evolution of the Biscay rift during the early Liassic

    SIMULATING EXOGENOUS SHOCKS IN COMPLEX SUPPLY NETWORKS USING MODULAR STOCHASTIC PETRI NETS

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    Almost all major companies are embedded in complex, global supply networks, consisting of multiple nested supply chains, and building up a high level of complexity. Exogenous shocks on these networks (e.g. natural disasters) can directly and indirectly impact companies and even cause their entire supply network to fail. However, today it is extremely difficult for a company to predict the actual impact of an exogenous shock on its supply network. Hence, companies are not able to identify adequate counteractive measures. Therefore safeguarding measures are oftentimes insufficient or even counterproductive. This paper deals with modelling, analyzing and quantifying impacts of exogenous shocks on supply networks using Petri Nets. It provides means to simulate the vulnerability of different network constellations regarding exogenous influences. In order to evaluate the proposed method, we simulate different intensities of an exogenous shock delaying the delivery for an exemplary supply network. We thereby illustrate which results could be yielded from a real-world application. For our exemplary network we find that the marginal effect of a disruption declines with an increasing intensity of shock. Moreover, the impact of shocks can be mitigated by appropriate counteractive measures like in this example by an increased safety margin of stock

    Opt: A Domain Specific Language for Non-linear Least Squares Optimization in Graphics and Imaging

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    Many graphics and vision problems can be expressed as non-linear least squares optimizations of objective functions over visual data, such as images and meshes. The mathematical descriptions of these functions are extremely concise, but their implementation in real code is tedious, especially when optimized for real-time performance on modern GPUs in interactive applications. In this work, we propose a new language, Opt (available under http://optlang.org), for writing these objective functions over image- or graph-structured unknowns concisely and at a high level. Our compiler automatically transforms these specifications into state-of-the-art GPU solvers based on Gauss-Newton or Levenberg-Marquardt methods. Opt can generate different variations of the solver, so users can easily explore tradeoffs in numerical precision, matrix-free methods, and solver approaches. In our results, we implement a variety of real-world graphics and vision applications. Their energy functions are expressible in tens of lines of code, and produce highly-optimized GPU solver implementations. These solver have performance competitive with the best published hand-tuned, application-specific GPU solvers, and orders of magnitude beyond a general-purpose auto-generated solver

    Aggregate and emulsion properties of enzymatically-modified octenylsuccinylated waxy starches

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    Sorghum and maize waxy starches were hydrophobically modified with octenylsuccinic anhydride (OSA) and treated with enzymes before being used to emulsify ÎČ-carotene (beta,beta-carotene) and oil in water. Enzyme treatment with ÎČ-amylase resulted in emulsions that were broken (separated) earlier and suffered increased degradation of ÎČ-carotene, whereas treatment with pullulanase had little effect on emulsions. Combinations of surfactants with high and low hydrodynamic volume (V) indicated that there is a relationship between V and emulsion stability. Degree of branching (DB) had little direct influence on emulsions, though surfactants with the highest DB were poor emulsifiers due to their reduced molecular size. Results indicate that V and branch length (including linear components) are the primary influences on octenylsuccinylated starches forming stable emulsions, due to the increased steric hindrance from short amphiphilic branches, consistent with current understanding of electrosteric stabilization. The success of OSA-modified sorghum starch points to possible new products of interest in arid climates

    Quantitative and Qualitative Analysis of Dynamic Cavernosographies in Erectile Dysfunction due to Venous Leakage

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    Of 521 patients with erectile dysfunction in whom a multidisciplinary approach was used, 145 (27.8%) showed venous leakage as (concomitant) etiology of the impotence in dynamic cavernosography. The rate of the maintenance flow corresponded well with the response to a standardized intracavernosal injection of vasoactive drugs (p < 0.05) in patients with venous leakage. The maintenance flow increased with the age in secondary impotent men. It was not statistically different in patients with or without concomitant arterial insufficiency (p = 0.19). Fifty-one of 145 patients (32.2%) presented a pathologic cavernosal drainage via a single venous system; 94/145 (64.8%) showed a combined venous leakage. The type of leakage corresponded neither to the maintenance flow nor to the response to intracavernosal injections. Our findings show that standardized intracavernosal testing and Doppler have a high predictive value for the status of the venous occlusive system. Exact evaluation of the type of leakage can be made by bidimensional cavernosography only
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